There are many challenges in topical drug delivery. The topical composition should deliver the active agent to the site of treatment, have desirable sensory characteristics, not leave an unpleasant residue on the surface of the skin, and not cause irritation or discomfort. Aerosol foams are known to be suitable for this purpose.
U.S. Pat. No. 7,387,807 to Callaghan et al. discloses a topical composition comprising an extract of feverfew, pharmaceutical excipients, cosmetic agents, and other biologically active substances, such as retinoids. The composition may be in the form of an emulsion such as a cream or lotion.
U.S. Pat. No. 7,326,408 to Angel et al. discloses a composition for the topical treatment of acne comprising one or more sunscreen agents and an antibacterial medication, where the composition may be in the form of a gel, spray, foam, lotion or other form suitable for application to the skin. The composition may further comprise an additional anti-acne medication, such as a retinoid (e.g. tretinoin, adapalene or tazarotene).
U.S. Pat. No. 6,730,288 to Abram describes an aerosol foam composition including an effective amount of a pharmaceutically active ingredient, an occlusive agent, an aqueous solvent, an organic cosolvent, the pharmaceutically active ingredient being insoluble in both water and the occlusive agent, and the occlusive agent being present in an amount sufficient to form an occlusive layer on the skin, in use.
US published application No. 2006/0292080 to Abram et al. describes an oil in water emulsion foam comprising: a vitamin or analogue thereof solubilized in the water phase and a stabilizer solubilized in the oil phase, an emulsifier, an occlusive agent, and an organic co-solvent, and no description of the particle size of the oil phase.
US published application No. 2006/0057168 to Larm et al. describes a process for the preparation of an oil in water microemulsion or sub-micron emulsion composition, in particular an oil in water microemulsion or sub-micron emulsion foam composition. These submicron or micro emulsion foams have a comparatively high oil content and require both a hydrophilic and a hydrophobic surfactant.
The present invention is directed to low oil and low surfactant submicron emulsions or microemulsion aerosol foams containing a pharmaceutically active agent, which are cosmetically elegant, chemically and physically stable, well tolerated, easy to formulate, and suitable for application to the face.